posted March 29, 2004 02:19 PM
Originally posted by 44nymod:
I run alky with gold series belt drive pump what should I set my idel at? Because the alternator doesn't charge until 1500RPM.
Don't worry about the alternator charging at idle - this is not where you're going to be running the car when racing and the battery should supply plenty of juice to keep the car running for the short idle times. That said - set the idle according to your engine builder's recomemdations - I've got a race engine that likes to idle around 8-900 RPM and one that doesn't want to idle below 1200... all in the heads/intake/cam setup.
I'm also having a problem with my charging system - I run an MSD box and distibutor electric fan and my alternator won't start charging until 1500 RPM's I know this because I called the guy that makes them. My problem is the car seems to want to turn over once or twice before the batter seems dead. Iv'e been all over this thing with a multi meter and I can't get this figured out. The batter is new and the only thing else I can figure is if my main power switch is going bad. One thing I did notice before I left the garage this afternoon is, I wiggled the master switch and the lights dimmed. Is there any way to check this switch? Any help would be greatly appreciated.
First - the charging system has almost NOTHING to do with "turning over" the engine - I say almost nothing because if the battery doesn't get charged sometime it won't have any current. SO... Charge the battery with a plug-in wall charger (we'll assume it's good since it's new), does the car still only want to crank once or twice?? If it does then it's not the battery (and you're not relying on the charging system yet)
A quick test can be done by doing the cranking and then having someone feel all the connections - the ones with high resistance will be warm to the touch. I'd check each cable end as a loose or corroded cable end will cause a high resistance that will reduce available current to the starter.
Assuming that this is a mod and the ground is via a solid motor mount / mid-plate - have you cleaned the motor mount to frame and mid-plate contact areas to ensure a good ground? (i.e. you didn't just paint all that real pretty and create an insulator) Also clean and check where the battery ground goes into the frame for the same.
If all the cabling checks out OK then swap the starter for a known good one - as yours may be drawing way too much current (have a short in the windings)
Last thing to try is to measure cranking voltage at each point in the system - at the battery, at the "input" of the switch, at the output of the switch, at the input of the ford-type solinoid (if you're using one), at the output, then at the starter-mounted solenoid - look for voltage drops below 8.x or 9v when cranking and look for any connection that is more than ~.1v less than the previous connection.
Try those things and post the results.